Thursday, July 12, 2012

U.S. Drought Coverage Expands to Decade-Plus High of 80%

Despite increased rainfall, the latest U.S. Drought Monitor report, released this morning, shows that the area covered by some level of drought increased to 80% in the week ending July 10. This is up from 76% last week and is the highest dryness at least since Drought Monitor statistics began in 2000. Although D4 (Exceptional) coverage is still well below the extremes reached last summer, drought area increased for all levels except the lowest, D0 (Abnormally Dry).

CapitalClimate analysis of National Weather Service data from 215 major reporting locations across the 48 contiguous states shows that total precipitation for the week ending July 7 was just 51.5% of normal. Weekly precipitation was less than 0.25" at 125 stations, or 58% of the total locations.

The Drought Monitor national summary:
Rainfall was more abundant than last week. A broken pattern of moderate to locally heavy rains (isolated totals up to 5 inches) covered the central and southern Plains, the northernmost Plains and Great Lakes region, the immediate Ohio Valley, and a good chunk of the Southeast and interior mid-Atlantic. However, the heavier amounts were fairly isolated, and with the hot weather that covered much of the central and eastern United States, only a few scattered areas of dryness and drought experienced significant improvement. In addition, the areas with the greatest temperature anomalies (average daily maxima 10 to 13 degrees above normal) generally coincided with an area of scant rainfall across the Midwest, northwestern Ohio Valley, and southern Great Plains, resulting in another week of widespread deterioration and expansion of dryness and drought in these regions.
Images (click to enlarge): U.S. percentage area of drought, weekly from January 4, 2011 through July 10, 2012, CapitalClimate chart from U.S. Drought Monitor data; U.S. Drought Monitor map for July 10, 2012

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